See my comment on here for more context of my investigation:
https://bugzilla.mozilla.org/show_bug.cgi?id=1779257#c9
The saved context is invalid once the function that called `getcontext`
returns. We need to call the `getcontext` while the frame where we called it is
still on the stack. That's why this patch is moving the call to `getcontext` to
parent function by inlining the SyncPopulate content by using a macro instead.
This has to be a macro instead of a function because stack pointer address will
be invalid once the `Registers::SyncPopulate` returns. I tried to change this
method to inline but that didn't help either.
Differential Revision: https://phabricator.services.mozilla.com/D170133
In the case of FramePointerStackwalk, the caller gives a pointer to the
top-most frame to walk from. There isn't really a reason to give a
number of frames to skip, as the right frame pointer could be given in
the first place if that was really necessary. And in practice, it's
hasn't been used so far.
In the case of MozStackWalkThread, the caller presumably doesn't know
what the thread the stack is being walked for is doing, and it would be
a guesswork to pass a valid number of frames to skip. In practice, it's
also not used.
The aSkipFrames is already a footgun on MozStackWalk (and we're going to
change that in bug 1515229), we don't need to keep a footgun on these
other stack walking methods.
Differential Revision: https://phabricator.services.mozilla.com/D108563
In most situations, JSONWriter users already know string lengths (either directly, or through `nsCString` and friends), so we should keep this information through JSONWriter and not recompute it again.
This also allows using JSONWriter with sub-strings (e.g., from a bigger buffer), without having to create null-terminated strings.
Public JSONWriter functions have overloads that accept literal strings.
Differential Revision: https://phabricator.services.mozilla.com/D86192
JSONWriter currently calls new and delete indirectly through mozilla::MakeUnique to allocate a buffer. Becuase of this, the methods of this class cannot be invoked within Spidermonkey due to https://searchfox.org/mozilla-central/source/config/check_vanilla_allocations.py#6-14. Therefore, JSONWriter needs an AllocPolicy template parameter so that the allocation and deallocation routines can be changed to match the JS AllocPolicy when invoked within SpiderMonkey.
Differential Revision: https://phabricator.services.mozilla.com/D7279
Entry storage allocation now occurs on the first lookupForAdd()/put()/putNew().
This removes the need for init() and initialized(), and matches how
PLDHashTable/nsTHashtable work. It also removes the need for init() functions
in a lot of types that are built on top of mozilla::Hash{Map,Set}.
Pros:
- No need for init() calls and subsequent checks.
- No memory allocated for empty tables, which are not that uncommon.
Cons:
- An extra branch in lookup() and lookupForAdd(), but not in put()/putNew(),
because the existing checkOverloaded() can handle it.
Specifics:
- Construction now can take a length parameter.
- init() is removed. Explicit length-setting, when necessary, now occurs in the
constructors.
- initialized() is removed.
- capacity() now returns zero when the entry storage is absent.
- lookupForAdd() is no longer `const`, because it can instantiate the storage,
which requires modifications.
- lookupForAdd() can now return an invalid AddPtr in two cases:
- old: hashing failure (due to OOM in the hasher)
- new: OOM while instantiating entry storage
The existing failure handling paths for the old case work for the new case.
- clear(), finish(), and clearAndShrink() are replaced by clear(), compact(),
and reserve(). The old compactIfUnderloaded() is also removed.
- Capacity computation code is now in its own functions, bestCapacity() and
hashShift(). setTableSizeLog2() is removed.
- uint32_t is used throughout for capacities, instead of size_t, for
consistency with other similar values.
- changeTableSize() now takes a capacity instead of a deltaLog2, and it can now
handle !mTable.
Measurements:
- Total source code size is reduced by over 900 lines. Also, lots of existing
lines got shorter (i.e. two checks were reduced to one).
- Executable size barely changed, down by 2 KiB on Linux64. The extra branches
are compensated for by the lack of init() calls.
- Speed changed negligibly. The instruction count for Bench_Cpp_MozHash
increased from 2.84 billion to 2.89 billion but any execution time change was
well below noise.
In PLDHashTable the equivalent functions have a "Shallow" prefix, which makes
it clear that they don't measure things hanging off the table. This patch makes
mozilla::Hash{Set,Map} do likewise.
MozReview-Commit-ID: 3kwCJynhW7d
This was done automatically replacing:
s/mozilla::Move/std::move/
s/ Move(/ std::move(/
s/(Move(/(std::move(/
Removing the 'using mozilla::Move;' lines.
And then with a few manual fixups, see the bug for the split series..
MozReview-Commit-ID: Jxze3adipUh
This makes things slightly more inconvenient (having to set two
environment variables instead of one for the simplest case) until a few
patches down the line, when DMD is statically linked, at which point it
will get down to one environment variable every time.
As of bug 1420353, DMD's replace_* functions can't be called before
replace_init places them in the malloc function table, which only
happens after DMD::Init has run, meaning DMD is always initialized
by the time any of its replace_* function can be called.
The original purpose of those declarations was to avoid the function
definitions being wrong, as well as forcing them being exported
properly (as extern "C", as weak symbols when necessary, etc.), but:
- The implementations being C++, function overloads simply allowed
functions with the same name to have a different signature.
- As of bug 1420353, the functions don't need to be exported anymore,
nor do we care whether their symbols are mangled. Furthermore, they're
now being assigned to function table fields, meaning there is type
checking in place, now.
So all in all, these declarations can be removed.
Also, as further down the line we're going to statically link the
replace-malloc libraries, avoid symbol conflicts by making those
functions static.
This makes things slightly more inconvenient (having to set two
environment variables instead of one for the simplest case) until a few
patches down the line, when DMD is statically linked, at which point it
will get down to one environment variable every time.
As of bug 1420353, DMD's replace_* functions can't be called before
replace_init places them in the malloc function table, which only
happens after DMD::Init has run, meaning DMD is always initialized
by the time any of its replace_* function can be called.
Sylvestre Ledru